It just got a lot easier to build OpenStack clouds in a place where they were once deemed unlikely: atop the VMware-virtualized environment of enterprise data centers.

VMware has formed a partnership with Mirantis to help its customers build OpenStack private clouds on top of their vSphere virtualized servers, as an alternative to using VMware's own vCloud option.

VMware plus Mirantis is an unlikely pairing. Mirantis is a leading consulting firm on OpenStack implementations and an OpenStack partisan that has frequently suggested its distribution of OpenStack is a better alternative to VMware's vCloud suite. Boris Renski, executive VP and co-founder of Mirantis, calls the VMware deal "a strategic partnership" that illustrates how both Mirantis and VMware "are trying to uphold customer choice."

Renski, the chief spokesman announcing the partnership, made his comments to InformationWeek from Hong Kong as the OpenStack Summit got underway there Tuesday morning. Renski is also one of the two members of the OpenStack Foundation's board of directors who voted against VMware joining the OpenStack project.

Asked to reconcile these two positions, Renski said: "I was originally skeptical. But VMware representatives have stopped their public disparagement of OpenStack, which they were doing at one time. VMware developers have made significant core contributions," Renski said.

It's well known that VMware's software-defined network talent, acquired through Nicira, has remained a contributor to the OpenStack networking project, Neutron. It's less well known that VMware developers "have contributed across several OpenStack areas of development to push the whole project forward," he said. In effect, Renski said, Mirantis has monitored VMware's participation and behavior and found that it wasn't oriented toward furthering only its own technologies. Such scrutiny is a common crowd litmus test applied to established vendors joining open source projects. A year after it became part of the project, Mirantis is saying VMware has passed.

That Mirantis statement may have been what VMware was seeking as much as OpenStack technical expertise. The Mirantis move may leave some other OpenStack partners, such as Red Hat, wishing the bar had been set higher for VMware. The default hypervisor in OpenStack clouds is Red Hat's KVM. Mirantis is making it easier for VMware customers to get OpenStack but keep their ESX Server virtual machines.

In addition, in June Red Hat offered its own distribution of OpenStack, called Red Hat Enterprise Linux OpenStack Platform. VMware is now committed to use the Mirantis OpenStack distribution, which will be closely integrated with VMware technologies.

If OpenStack was once seen as a challenger and disrupter of VMware's hold on the data center, the ability to disrupt VMware's grasp just moved a little further back out over the horizon.

Renski said Mirantis customers are often implementers of vSphere, VMware's virtual machine provisioning and monitoring environment, and they are expressing interest in VMware NSX network virtualization platform as well. "This partnership will help us provide the best possible experience for them," claimed Renski.

One of the things that will be done through the partnership is to tie Mirantis' Fuel library of compatible OpenStack code modules, which have been tested for deployment with different versions of OpenStack, such as Suse Linux OpenStack or Ubuntu OpenStack. Mirantis' further development of Fuel will allow the OpenStack compute service, Nova, to be integrated with VMware's vCenter driver. vCenter is used to move VMware workloads around the data center and monitor them.

In addition, Fuel will be integrated with VMware's NSX networking platform driver to allow OpenStack networking to use NSX services. Cisco has its own approach to virtualized networking. If OpenStack on top of VMware catches on, use of VMware's NSX may prompt Cisco to also wish Mirantis had set the VMware-endorsement bar at a higher level.

Work between Mirantis and VMware will allow the OpenStack Cinder project to automatically configure a block storage service to work with the VMware virtual machine file format's VMDK data-store driver. In addition, the VMware-Mirantis partnership will ensure that VMware technologies continue to work with the latest OpenStack releases. OpenStack recently launched the Havana release; the foundation issues two releases each year.

Mirantis accepted $10 million in venture capital funding last January; at the time it had 300 employees and was self-sustaining from its consulting work.